45/64" drill size
A 45/64 in drill is 0.7031 in (17.86 mm). It sits between 11/16 in and 23/32 in in the fractional series; the nearest metric drill is 17.9 mm.
45/64" at a glance
Decimal, metric and the nearest sizes in the other series.
Nearest metric drills
Metric drills step by 0.05 mm below 3 mm and by 0.1 mm from 3 mm. Difference is metric minus inch size.
| Metric drill | Inch | Difference | In inches | Hole |
|---|---|---|---|---|
| 17.8 mm | 0.7008" | −0.059 mm | −0.0023" | Smaller |
| 17.9 mm | 0.7047" | +0.041 mm | +0.0016" | Larger |
Nearby inch drills
The next size down and up in each inch series, so you can pick a substitute from the drawer.
Threads a 45/64" drill can tap
Threads from the tap tables on this site that this drill can tap, with the thread percentage it leaves (55–85 % shown).
| Thread | Standard drill | Thread with this drill | Suits |
|---|---|---|---|
| M20 × 2.5 | 17.5 mm | 66 % | Good in steel |
| 3/4-16 UNF | 11/16 | 58 % | Hard, tough metals |
Clearance for screws and bolts
Bolts and screws a 45/64" hole clears, with the diametral clearance and the gap each side. Metric sizes are compared with ISO 273.
| Fastener | Diameter | Clearance | Per side | ISO 273, metric only |
|---|---|---|---|---|
| M16 bolt | 16 mm | 1.86 mm | 0.93 mm | Normal fit (normal 17.5, loose 18.5 mm) |
Inch clearance is the drill size minus the basic major diameter. A drilled hole usually cuts slightly oversize.
Fractional drill index
Every size in the series, holes drawn to scale.
Common questions
What size is a 45/64 in drill?
A 45/64 in drill is 0.7031 in, which is 17.86 mm (17.8594 mm exactly).
What is the metric equivalent of a 45/64 in drill?
The nearest metric drill is 17.9 mm, 0.041 mm larger. The other close size is 17.8 mm.
What thread can I tap with a 45/64 in drill?
It leaves about 66 % thread in M20 × 2.5 and 58 % in 3/4-16 UNF.
What does a 45/64 in drill clear?
It clears a M16 bolt with 1.86 mm total clearance (0.93 mm per side); for metric bolts: normal fit.